SHAFAQNA -Â Muslims in France are once again in doubt over the exact date that the holy month of Ramadan begins, with two competing schools of thought on how the date should be decided.

The holy month of Ramadan â€“ during which observant Muslims fast by day, eat in the hours of darkness and celebrate the final day with lavish feasting â€“ is the most important event in the Islamic calendar. But when does it begin?

According to the French Union of Islamic Organisations (UOIF), which is linked to the Muslim Brotherhood, Ramadan’s start date this year is June 18, having been decided in advance by calculating the lunar cycle.

But the French Council of the Muslim Faith (CFCM) will wait to witness the new moon and has yet to pronounce a start date for the fast.

The latter method follows aÂ hadith (a teaching of the Prophet Mohammed) that states: â€œDo not start fasting unless you see the new moon, and do not end fasting until you see it.â€

TheÂ hadith continues, however: â€œIf the weather is cloudy then calculate when it should appear.â€

So while many Muslims in the modern era calculate the date in advance and have precisely fixed dates that allow the faithful to prepare, others prefer to do it by the book and wait until the new moon is visible.

The sighting of the new moon will occur at different times around the world, however, so a Muslim in France may end up starting the Ramadan fast on a different day than a Muslim based in Saudi Arabia.

And if there is any doubt, perhaps due to cloud cover, the mosque will follow the example of other Muslim countries â€“ notably Saudi Arabia, which nearly always has the last word.

The CFCM, which is dominated by Muslims of Moroccan and Algerian descent and is supported by the countryâ€™s Salafists, even created a lunar observatory in 2014 to avoid any mistakes. It preaches that waiting to witness the new moon â€œis supported by the great majority of believersâ€.

Will the moon be visible?

The UOIF, meanwhile, has said that viewing the new moon might be impossible on June 16 because the moon will be in the visible range only before the sun sets on that date. June 16 is one of the longest days of the year, coming less than a week before the summer solstice.

â€œThe first day of the holy month of Ramadan for the year 1436 (of the Muslim calendar) will be on June 18, by the Will of God,â€ the organisation said in a statement.

And with both sides convinced of their methods, the vagaries of weather and lunar visibility are not the only variables that will ultimately determine when French Muslims will begin marking the holiest month of the year.